Every year, tens of millions of Americans suffer from nerve damage, some irreparably
so.
Science can heal bones, grow new organs and even restore our microbiomes, but why is it
so hard to fix our nerves?
Hey guys Lissette here for DNews
The human body posses a remarkable ability to heal.
Bones re-fuse, skin wounds mend, and the immune system adapts to infection, after infection.
But there’s one area of the body that struggles to recover after an injury: The nervous system.
Nerve damage can be some of the most debilitating and permanent type of injury.
The nervous system is an incredibly complex network used to send electrical information
throughout your body.
It can basically be divided into two sections.
With the brain and spinal cord making up the central nervous system or CNS…. and the
nerves made up of fibers of sensory and motor neurons comprising the peripheral nervous
system.
Each cell in the nervous system from the tip of your finger up your arm, up your spinal
column, into your brain, is very specialized.
And each has a unique function on the pathway, like a circuit.
If one these gets cut or injured, it’s hard for an exact replacement cell to be put in
in the right spot.
Think about when you get a cut on your skin.
If the cut goes deep enough, exact replicas of cells won't cover the wound, instead fibrous
tissues form... which we call scars.
And scars are part of the problem in regrowing nerves, they often get in the way - especially
in the case of spinal cord injuries.
As part of the CNS, spinal cord injuries are notoriously difficult to heal; partially because
of the way nerve cells in the CNS are made.
According to the book, “Results and Problems in Cell Differentiation”, the CNS also has
certain proteins that weirdly, inhibit cell regeneration.
While this might sound like a bad idea, it’s hugely beneficial overall to the formation
of the CNS.
These cells need to grow exactly where they are supposed to, just one out of place could
be bad.
Like... think of an electrical circuit, each unit has to be in a specific order in specific
place to work.
If one is out of place, the integrity of the CNS is compromised.
Neurons in the CNS also lack certain cleaning cells.
Nerve cells are made up of many parts, but they send signals through threads covered
in a protective sheet of myelin.
These threads are called axons.
Axons are the long part of the cell that reaches out to the cell next to it to send information
down the line...
Like arms handing the bucket down the line in a bucket brigade.
So these are obviously super important and need protecting.
That’s where the Schwann cells come in... which are only found in the Peripheral nervous
system.
Schwann cells, which aren’t neurons but GLEEL cells, produce the myelin that help
protect the axons.
But, a study published in The Journal of Cell Biology found they also clean up damaged nerves
- making way for the healing process to take place and new nerves to be formed.
But the problem is... these Schwann cells are missing from the CNS.
What they have instead are myelin producing cells called oligodendrocytes.
But these cells don’t clean up damaged nerve cells at all.
Which is part of the problem.
So unfortunately, according to Dr. Richard G. Fessler professor at Rush University Medical
Center "There are currently no therapies which successfully reverse the damage" from injuries
to the spinal cord.
But research is currently underway to examine the potential success of stem cell treatment,
where stem cells are injected directly at the injury site.
Still, it will take a few years to see the results of such trials.
But there are times your body can regenerate nerves.
The peripheral nervous system doesn’t have the same blocking proteins that the CNS has,
and Schwann cells help heal the damage.
So it’s able to regrow nerves, albeit slowly.
For instance, if you cut a nerve into your shoulder, it could take a year to regrow.
By that time...the muscles in your arms could become atrophied.
So, not surprisingly, researchers are working on helping the body heal faster.
One study published in the Journal of Clinical Investigation found that a shock of heat made
the peripheral nerves grow faster.
In another study published in the journal Advanced Functional MATERIALS, researchers
used 3D printing to make a sort of guide for peripheral nerves to follow as they regrew.
The guide was built with small physical grooves and even chemical cues to help guide the nerve
along its new path.
But, to learn more about other research into repairing spinal cord injuries, check out
Trace
in this episode right here